Apparatus and method for compensating for stress deformation in a press

Abstract

A method for locally increasing pressing pressure on a press tool having an abutment surface for being clamped onto a clamping surface in a press comprises providing a power unit smaller than the abutment surface and having an internal space, positioning the power unit between the clamping surface and the abutment surface, pressing the clamping surface against the abutment surface, connecting the internal space to a source of pressurized hydraulic fluid, and supplying the pressurized hydraulic fluid to the internal space thereby causing the power unit to expand and to exert a local pressure on the abutment surface.

Description

CROSS REFERENCE TO RELATED APPLICATION(S)[0001]This application is a divisional application of U.S. patent application Ser. No. 10 / 582,591, filed Apr. 17, 2007, entitled APPARATUS AND METHOD FOR COMPENSATING FOR STRESS DEFORMATIONS IN A PRESS.BACKGROUND[0002](1) Field of the Invention[0003]The present invention relates to an apparatus for compensating for such deformations as occur in first and second clamping surfaces intended for a tool in a press, the clamping surfaces being reciprocally moveable towards and away from one another for moving a first and a second part of the tool towards and away from each other, respectively, such deformations generating an uneven pressure in at least one area of contact between the tool and the clamping surfaces.[0004](2) Prior Art[0005]In hydraulic presses, tools are positioned by means of which different objects are compression moulded to the desired configuration and appearance. Hydraulic presses operate at high pressure, which results in the ...

AI Technical Summary

Benefits of technology

[0012]The present invention enjoys the following advantages. The apparatus according to the present invention may be formed and given a thickness which is sufficiently great where required and sufficiently thin where required over a surface in a press, in order thereby to compensate for deformations which occur. The high level of flexibility of the invention makes it easier to compensate for a new tool which is placed in the press, which results in shorter retooling time and higher production capacity in the press. Thus, the apparatus according to the invention enjoys the advantage that its thickness is variable.

Problems solved by technology

Hydraulic presses operate at high pressure, which results in the parts in the hydraulic press, as well as the tool placed in the hydraulic press, being subjected to extreme stresses.

These stresses are so great that the parts of the hydraulic press and the tool are deformed.

This deformation results in the pressure distribution in those tools which are to impart to the final product its configuration and appearance becoming uneven.

This will have as a result that the end product will be unevenly formed and will have an unacceptable quality.

The drawbacks inherent in prior art technology are numerous.

In the utilisation of shims, there is, granted, obtained a compensation for the deformation, but accurate setting is required and, this not withstanding, the compensation will be incomplete and above all not constant, but the compensation itself must be repeated at regular intervals.

This results in unnecessary time loss for the compensation which lowers production capacity for the press.

Another drawback inherent in shims is further that the thickness of the shims is given and not variable.

Accuracy using shims is also difficult to achieve, which has a negative effect on the quality of the product produced using the tool in the press.

The drawback inherent in cambering or crowning is that the arching which is created is difficult to change in a simple manner if required.

This lack of flexibility also results in considerable time loss when a new tool is to be positioned in a press.

Hence, cambering or crowning shows a low level of flexibility.

In addition, there has been a lack of an apparatus which simply and rapidly can be adapted to a new tool disposed in a press.

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